text: /** @file
   *
   *  A key generator for QUIC connection
   *
   *  @section license License
   *
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF licenses this file
   *  to you under the Apache License, Version 2.0 (the
   *  "License"); you may not use this file except in compliance
   *  with the License.  You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   */
  #pragma once
  
  #include <openssl/evp.h>
  #include "QUICTypes.h"
  #include "QUICHKDF.h"
  
  #ifdef OPENSSL_IS_BORINGSSL
  typedef EVP_AEAD QUIC_EVP_CIPHER;
  #else
  typedef EVP_CIPHER QUIC_EVP_CIPHER;
  #endif // OPENSSL_IS_BORINGSSL
  
  class QUICKeyGenerator
  {
  public:
    enum class Context { SERVER, CLIENT };
  
    QUICKeyGenerator(Context ctx) : _ctx(ctx) {}
  
    /**
     * Generate keys for Initial encryption level
     * The keys for the remaining encryption level are derived by TLS stack with "quic " prefix
     */
    void generate(uint8_t *hp_key, uint8_t *pp_key, uint8_t *iv, size_t *iv_len, QUICConnectionId cid);
  
    void regenerate(uint8_t *hp_key, uint8_t *pp_key, uint8_t *iv, size_t *iv_len, const uint8_t *secret, size_t secret_len,
                    const QUIC_EVP_CIPHER *cipher, QUICHKDF &hkdf);
  
  private:
    Context _ctx = Context::SERVER;
  
    uint8_t _last_secret[256];
    size_t _last_secret_len = 0;
  
    int _generate(uint8_t *hp_key, uint8_t *pp_key, uint8_t *iv, size_t *iv_len, QUICHKDF &hkdf, const uint8_t *secret,
                  size_t secret_len, const QUIC_EVP_CIPHER *cipher);
    int _generate_initial_secret(uint8_t *out, size_t *out_len, QUICHKDF &hkdf, QUICConnectionId cid, const char *label,
                                 size_t label_len, size_t length);
    int _generate_key(uint8_t *out, size_t *out_len, QUICHKDF &hkdf, const uint8_t *secret, size_t secret_len,
                      size_t key_length) const;
    int _generate_iv(uint8_t *out, size_t *out_len, QUICHKDF &hkdf, const uint8_t *secret, size_t secret_len, size_t iv_length) const;
    int _generate_hp(uint8_t *out, size_t *out_len, QUICHKDF &hkdf, const uint8_t *secret, size_t secret_len, size_t hp_length) const;
    size_t _get_key_len(const QUIC_EVP_CIPHER *cipher) const;
    size_t _get_iv_len(const QUIC_EVP_CIPHER *cipher) const;
    const QUIC_EVP_CIPHER *_get_cipher_for_initial() const;
    const QUIC_EVP_CIPHER *_get_cipher_for_protected_packet(const SSL *ssl) const;
  };
  